Theoretical study on the smallest endohedral metallofullerenes: TM@C _(20) (TM = Ce and Gd)

摘要

The structure, electronic property, and infrared spectroscopy of endohedral metallofullerenes TM@C_(20) (TM = Ce and Gd) have been systematically investigated with the aid of the hybrid DFT-B3LYP functional. It is found that in the endohedral metallofullerenes the average C-C bond lengths are obvious longer than those of empty cage. The frontier orbital analyses show that the endohedral metallofullerene Gd@C_(20) has the high-thermodynamic stability. Natural population analysis also tells us that only in the Ce@C _(20), the Ce atom acts as an electron acceptor with the negative charges, and the 4f orbitals of Ce and Gd atoms have a significant contribution in the formation of chemical bonding. Additionally, the analyses of harmonic vibrational frequencies reveal that when the TM atoms are encapsulated into the C_(20) cage, the strongest absorption peaks are characterized by a mixture of TM-C bending and C-C stretching vibrations.